Well you should move up when you have 30 buyins for a new limit, according to bankroll management strategy articles on ps.com. So yes, you can move up, although some players use te "50BI rule". Gives u more coushin and stability against variance. So if u feel comfortable just move up, otherwise stay on nl10 for a bit longer.
Oh, and the difference in nl10 and nl25 is just in the numbers